This invention is generally directed to imaging members, and more specifically, the present invention is directed to single and multilayered photoconductive imaging members with a hole blocking, or undercoat layer (UCL) comprised of, for example, a pyrolyzed polyacrylonitrile, and which pyrolyzed polyacrylonitrile can in embodiments be overcoated, dispersed in a suitable binder, and the like, depending, for example, on the form of the layer, that is when applied as a continuous layer the pyrolyzed polyacrylonitrile is preferably overcoated with a silane material, such as 3-aminopropyltriethoxysilane (APS). Moreover, in embodiments the pyrolyzed polyacrylonitrile can be dispersed in a binder of, for example, a binder comprised of a phenolic resin, reference U.S. Pat. Nos. 6,255,027; 6,177,219, and 6,156,468, and which layer can be deposited on a supporting substrate. More specifically, the hole blocking layer in contact with the supporting substrate can be situated between the supporting substrate and the photogenerating layer, which is comprised, for example, of the photogenerating pigments of U.S. Pat. No. 5,482,811, the disclosure of which is totally incorporated herein by reference, especially Type V hydroxygallium phthalocyanine, and generally metal free phthalocyanines, metal phthalocyanines, perylenes, titanyl phthalocyanines, selenium, selenium alloys, and the like. The imaging members of the present invention in embodiments exhibit excellent cyclic/environmental stability, and substantially no adverse changes in their performance over extended time periods, since the imaging members comprise a mechanically robust and solvent resistant hole blocking layer, enabling the coating of a subsequent photogenerating layer thereon without structural damage; excellent Vlow, that is the surface potential of the imaging member subsequent to a certain light exposure, minimal or substantially no plywood effects, excellent charge acceptance, low dark decay, rapid voltage discharge decay curves, low voltage residuals, and which blocking layer can be easily coated on the supporting substrate by various coating techniques of, for example, dip or slot-coating. The aforementioned photoresponsive, or photoconductive imaging members can be negatively charged when the photogenerating layers are situated between the hole transport layer and the hole blocking layer deposited on the substrate.
Processes of imaging, especially xerographic imaging and printing, including digital, are also encompassed by the present invention. More specifically, the layered photoconductive imaging members of the present invention can be selected for a number of different known imaging and printing processes including, for example, electrophotographic imaging processes, especially xerographic imaging and printing processes wherein charged latent images are rendered visible with toner compositions of an appropriate charge polarity. The imaging members as indicated herein are in embodiments sensitive in the wavelength region of, for example, from about 500 to about 900 nanometers, and in particular from about 650 to about 850 nanometers, thus diode lasers can be selected as the light source. Moreover, the imaging members of this invention are useful in color xerographic applications, particularly high-speed color copying and printing processes.
The imaging members illustrated herein and containing an undercoat layer of pyrolyzed polyacrylonitrite (PPAN) is substantially insensitive to (1) solvents, such as organic solvents, like methylene chloride; (2) changes in environmental conditions and heat; and is (3) substantially anti-reflective thereby suppressing plywood print pattern defects; and (4), thicker undercoat layers can be selected resulting, for example, in photoconductive members with economical substrates.